Bioenergetics

Question 1

What do plants use as a source of energy?

Answer 1

Light from the sun

Question 2

What is the name of the reaction that traps energy for plants

Answer 2

Photosynthesis

Question 3

What type of reaction is photosynthesis?

Answer 3

Endothermic because it takes in energy

Question 4

Where does photosynthesis take place in?

Answer 4

The leaf

Question 5

How does photosynthesis occur?

Answer 5

Plant takes in carbon dioxide and water
The chlorophyll in chloroplasts absorb light energy
Light energy used in reaction to concert CO2 and H2O into glucose and oxygen

Question 6

Photosynthesis word equation

Answer 6

Carbon dioxide + water ——> Glucose + Oxygen

Question 7

Photosynthesis symbol equation (unbalanced)

Answer 7

CO₂ + H₂O ——> C₆H₁₂O₆ + O₂

Question 8

Limiting factor in photosynthesis

Answer 8

When a factor lowers the rate of photosynthesis
So if you increase it the rate of photosynthesis will increase
But eventually rate stops increasing as something else becomes limiting factor

Question 9

What could be a limiting factor?

Answer 9

Light intensity
Carbon dioxide level
Amount of chlorophyll
Temperature

Question 10

Amount of chlorophyll as a limiting factor

Answer 10

The leaf will trap less light if there are low levels of chlorophyll in the leaf
Making it a limiting factor

Question 11

How are limiting factors shown on a graph for photosynthesis
(CO2, chlorophyll, light intensity)?

Answer 11

The rate will increase as the factor increases showing it couldn’t have increased before as there wasn’t enough
It straightens off when it no longer is a limiting factor

Question 12

Temperature as a limiting factor

Answer 12

Increasing it will increase rate of reaction
But if you increase it over the enzymes optimum it will denature and rate will fall

Question 13

How is temperature limiting factor graph shown?

Answer 13

Rate increase as temperature increases
But falls to 0 as it reaches optimum temperature

Question 14

What can plants use glucose from photosynthesis for?

Answer 14

For respiration to release energy
Starch
Fats and oils
Cellulose
Amino acids

Question 15

Why do plants store glucose as starch?

Answer 15

It is insoluble
So can be stored and then converted back into glucose if they need it for respiration
Because at night time they cannot make more glucose with no photosynthesis so they can use the stored starch instead

Question 16

Why do plants convert glucose to fats and oils?

Answer 16

As a storage form of energy

Question 17

Why do plants make cellulose from glucose?

Answer 17

Because it strengthens the cell wall which keeps it from bursting

Question 18

Why do plants make amino acids from glucose?

Answer 18

Amino acids are needed for protein synthesis

Question 19

How do plants make amino acids from glucose?

Answer 19

From nitrate ions

Question 20

How can we determine what the limiting factor is?

Answer 20

Increase the amount of another factor and record the rate of photosynthesis
If the rate increases then that was the limiting factor
If not repeat with another factor

Question 21

Why do farmers want to increase the rate of photosynthesis

Answer 21

It increases yield of crops they want to produce

Question 22

How do farmers increase the rate of photosynthesis?

Answer 22

Oil burners = increase heat and carbon dioxide
Greenhouse = light heat and carbon dioxide increase

Question 23

Problem with increasing yield

Answer 23

Methods of increasing yield are expensive so the yield has to be justified

Question 24

What do humans need energy

Answer 24

Movement
Maintain body temperature
Chemical reactions to build larger molecules

Question 25

How do humans get energy

Answer 25

Respiration

Question 26

What type of reaction is respiration

Answer 26

Exothermic because it releases energy

Question 27

Aerobic respiration word equation

Answer 27

Glucose + oxygen ——> carbon dioxide + water + (energy)

Question 28

Why does aerobic respiration release a lot of energy?

Answer 28

Because the glucose molecule has been fully oxidised

Question 29

Aeróbic symbol equation

Answer 29

C₆H₁₂O₆ + O₂ ——> CO₂ + H₂O

Question 30

Anaerobic respiration

Answer 30

Happens when not enough oxygen is present

Question 31

Anaerobic respiration word equation in muscles

Answer 31

Glucose ——> Lactic acid+ (energy)

Question 32

Why does anaerobic respiration not release as much evidence?

Answer 32

Because the glucose molecule has not been fully oxidised

Question 33

Anaerobic respiration in plant/yeast cells

Answer 33

Glucose ——> ethanol + carbon dioxide

Question 34

Uses of yeast anaerobic respiration

Answer 34

Can make alcoholic drinks like beer Can make bread as the carbon dioxide causes bubbles in the dough = rise

Question 35

Name for yeast anaerobic respiration

Answer 35

Fermentation

Question 36

Why do we need more energy during exercise?

Answer 36

For muscle contraction

Question 37

What changes with the body cells during exercise?

Answer 37

Increase in aerobic respiration Therefore body cells demand more oxygen

Question 38

If the body cells demand more oxygen, what do we do?

Answer 38

Breathing rate and volume increases (more frequent deeper breaths) To get more oxygen in blood stream So heart rate increases to bump the oxygenated blood around

Question 39

What is the problem with exercising?

Answer 39

Not enough oxygen can be supplied to muscles especially if exercise is too vigorous So we can’t aeróbically respire

Question 40

What do we do once we don’t have enough oxygen for aerobic respiration?

Answer 40

Respire anaerobically But the oxidation of glucose incomplete = lactic acid builds up

Question 41

What happens when lactic acid builds up?

Answer 41

If we do a lot of vigorous activity = lactic acid makes muscles fatigued So stop contracting efficiently

Question 42

What do we do when muscle fatigue happens?

Answer 42

We need to remove the lactic acid by oxidising it Therefore enter a condition called oxygen debt

Question 43

How is lactic acid removed from muscles?

Answer 43

Transported out in the blood to the liver Converted back to glucose in chemical reactions using oxygen

Question 44

Oxygen debt

Answer 44

The oxygen required to convert the lactic acid that has built up back to glucose

Question 45

Metabolism

Answer 45

The sun of all chemical reactions in a cell or the body

Question 46

How is metabolism and respiration linked?

Answer 46

Respiration releases energy Which is used by enzymes to synthesise new molecules in a cell in chemical reactions Metabolism = sum of these reactions

Question 47

Uses of glucose in plants

Answer 47

Cellulose = strengthens cell wall Starch = storage form of glucose Reacts with nitrate ions = amino acids = protein synthesis Converted to fats and oils = storage form of energy

Question 48

Uses of glucose in humans

Answer 48

Glycogen = storage form released if blood sugar levels fall too low Aerobic respiration

Question 49

Metabolism reaction for lipid

Answer 49

1 glycerol molecules 3 fatty acid molecules

Question 50

Where are lipids found?

Answer 50

In the cell membrane

Question 51

Metabolism reaction involving excess protein

Answer 51

Excess protein —> urea —> excreted